Exhaust pipe assembly for pneumatic tools



v May 20, 1969 M. c. HUFFMAN 3,444,692

EXE'IAUST PIPE ASSEMBLY FOR PNEUMATIC TOOLS Filed Aug. 31. 1967INVENTOR. I l E. 3 MERV/N C HUFFMAN ATTORNEY United States Patent3,444,692 EXHAUST PIPE ASSEMBLY FOR PNEUMATIC TOOLS Mervin C. Hufiman,Denver, Colo., assignor to Gardner- Denver Company, a corporation ofDelaware Filed Aug. 31, 1967, Ser. No. 664,864 Int. Cl. F01b 31/02,31/16 US. C]. 6064 2 Claims ABSTRACT OF THE DISCLOSURE An exhaust pipeassembly for pneumatic tools, particularly applicable to percsussiontype tools, consisting of a swivelly mounted curved tubular conduit incombination with a flexible inner sleeve fixed at one end relative tothe outer surrounding conduit. The inner sleeve is of a flexiblematerial such as neoprene and is subject to flexing and vibratingmovement in response to the kinetic energy transmitted to it from theexhaust fluid pulsations emitting from the tool working chamber. Theflexing inner sleeve serves to break up and prevent the lodging of icein the tool exhaust system and also serves as a simple yet effectivemufller of the exhaust noise generated by the tool working fluid.

Background of the invention The application of pneumatic rock drills andsimilar pneumatic expansion devices in underground operations such astunneling and mining work usually produces a considerable amount of fogin the vicinity of the work area due to rapid expansion and cooling ofthe compressed air used to power the tools. The climatic conditionsusually present in mines and tunnels are quite conducive to this fogformation and in addition the exhausting of the compressed air from thetools produces a noise level in the area often uncomfortable if notintolerable to personnel. As a result it is common practice to conductthe exhaust from pneumatic rock drills and associated equipment tolocations remote from the immediate Work area by means of flexible hosesor the like attached directly to the exhaust ports of the tools. In thisway fog, objectional fumes, and high noise levels near the tools areavoided. However, a condition which is often unavoidable near theexhaust ports of rock drills and the like, particularly when the exhaustis conducted through a closed conduit, is the formation and accumulationof ice immediately downstream of the exhaust port and in the exhaustpipe or hose, again, due to a well understood cooling phenomena whichalso produces the aforementioned fog. This ice accumulation is oftensubstantial to the extent that the tool becomes inoperative after ashort period of time due to blockage of the exhaust system. This iceaccumulation usually occurs where directional change of some magnitudeis given to the exhaust flow so that the small ice particles present inthe fluid stream impinge and accumulate over a relatively small area.

The invention disclosed herein is somewhat analogous in purpose to theknown prior art in the patents to Fuehrer 2,128,742, Morrison 2,166,218,and Jordan 3,164,962 each of which has a vibrating element fixed to acasing surrounding the tool proper and constituting an integral part ofthe tool body. It is, however, apparent that the prior art fails todisclose an external tool attachiment that may be positioned within theexhaust flow path 3,444,692 Patented May 20, 1969 'ice of a conventionaltool and provided with vibrating means agitated by tool exhaust for thepurpose of preventing accumulation of ice crystals in the exhaust flowpath.

Summary of the invention.

The invention disclosed brings solutions to the problems of prohibitingice formation and accumulation as .well as contributing to theattenuation of noise in the exhaust system of pneumatic power tools byproviding an exhaust control means having a flexible sleeve of asuitable material held in spaced relation to an outer conduit and fixedatone end relative thereto. The conduit means is curved to assureimpinging flow of the exhaust fluid on the flexible sleeve which resultsin the flexing and vibrating of the sleeve to prevent the accumulationof ice and to absorb a substantial amount of the pressure wave energyusually manifested as audible sound.

An object of the invention is the provision of a smooth surfaced,surroundingly disposed, flexible conducting means for the exhaust flow,wherein possible locations for the lodging of ice particles areeliminated by a simple yet effective structure of great reliability.

It is also an object of the invention to provide an exhaust controlapparatus that can have secured to its free end a flexible hose of anydesired length through which the final exhaust composed of broken iceparticles or water and objectionable fumes may be conducted to a pointremote from the operator. To facilitate handling of the tool with theexhaust hose attached, the manifold is swivelly mounted on the tool forease in handling and positioning.

Brief description of the drawing FIG. 1 is a front elevation, partly insection, of a conventional percussion tool having associated therewiththe elements of the invention.

FIG. 2 is an enlarged sectional view showing a part of the tool cylinderand its exhaust passage having attached thereto the exhaust pipeassembly and the elements swivelly connecting the two.

FIG. 3 is an end view of the pipe assembly taken along the line 33 ofFIG. 2 illustrating the locking means for preventing movement of thelocking nut on the pipe assem bly when the latter is swung relative tothe tool casing.

Description of the preferred embodiments Referring to the accompanyingdrawing in detail, particularly FIG. 1, a conventional pneumaticpercussion tool, generally designated by the numeral 10, has anexpansible chamber defined by a reciprocating piston 12 and a cylinder14. An exhaust port 16 communicates the cylinder 14 with the partiallythreaded bore 18 of a boss 20 disposed on the side of the tool casing22. Positioned within the bore 18 is one end of an exhaust pipe assembly24 having therein an element vibrated by the exhaust fluid pulsationspassing therethrough. The pipe assembly 24 comprises a bent or curvedtubular member 25 having connected to its free end, by any suitablemeans, a flexible hose 26 through which the exhaust flow may beconducted to a suitable point usually remote from the tool and theoperating personnel.

FIG. 2 illustrates in detail the elements comprising the exhaust pipeassembly 24 including those elements used for swivelly connecting thepipe assembly to the boss 20 on the tool casing 22. In the pipe assemblyillustrated, the outer tubular member 25 is preferably constructed of apiece of steel tubing machined to provide the grooves, relieved section,and flanges to be explained later in detail. A preferred method ofobtaining the desired bent shape of the tubular member 25 is to cut oneor more V-shaped notches all in the same longitudinal plane after themachining process. The tubular member 25 is then heated and bent untilthe edges of the V-shaped notches abut each other wherein they arejoined by welding or an equivalent process.

Near the upper end of the tubular member 25 is an internal annulargroove 28 which interfittingly receives an external flange 32 formed asan integral part of a flexible curved inner sleeve 34. Adjacent to theflange 32 the flexible sleeve 34 fits snugly in the bore 36 of thetubular member 25. The remaining major portion 35 of the flexible sleeve34 is thereby held in fixed spaced relation to the internally relievedmajor portion 30 of the tubular member 25. To assist in maintaining theflexible sleeve 34 in fixed relation with the tubular member 25 a shortmetal tube 38 is pressed into a reduced bore portion 40 at the extremeupper end of the tubular member 25, as viewed in FIG. 2; and, the tube38 compressively engages the inner wall 42 of the flexible sleeve 34.The upper end of the metal tube 38 is flared to fit tightly within thebeveled end 44 of the tubular member 25. Albeit many materials are wellknown that would be suitable for the construction of the flexible sleeve34, a particularly suitable sleeve is obtained when molded of one of thechloroprene elastomers, such as neoprene, which has resiliency, can bemolded with a high degree of surface smoothness, and is relativelyimpervious to chemical substances.

For swivelly mounting the exhaust pipe assembly 24 on the pneumatic tool10 the tubular member 25 is journaled in an externally threaded collar46.

The threaded collar 46 is secured to the boss 20 by being screwed intothe partially threaded bore 18 until a flange 74 on the collar 46 istight against the face 70 of the boss 20. A gasket 72 is interposedbetween the flange 74 and the face 70 to prevent leakage of exhaustfluid therearound. A seal is also affected around the bore of the collar46 by an O-ring 50 in a groove 52 sealingly engaging the outer diameterof tubular member 25. Limited axial movement of the tubular member 25 inits journaled relationship with the collar 46 is maintained by a lockingnut 54 threaded over a reduced diameter portion 56 at the upper end ofthe tubular member 25, and by an external annular flange 48 projectingfrom the outer diameter of the tubular member 25 below the flange 74 onthe collar 46. With the locking nut 54 screwed tightly against theshoulder 58 on the tubular member 25 suflicient axial play of thetubular member 25 relative to the collar 46 is maintained to allow thetubular member 25 to swivel freely.

The locking nut 54 is secured to the tubular member 25, for theprevention of unscrewing of the nut from the tubular member 25, by aretaining ring 60 shaped to be biased to seat in a groove on the lockingnut 54. Referring to FIG. 3, the retaining ring 60 has one end bent toform a tab 62 which projects through a slot 64 in the locking nut 54 andinto a slot 66 in the reduced diameter portion 56 of the tubular member25. Should the slot 64 in the locking nut 54 not be in radialregistration with the slot 66 in the reduced diameter portion 56 whenthe locking nut 54 is threaded down tight against the shoulder 58, thenut may be unscrewed until said radial registration occurs with theresulting increased axial play allowed the tubular member 25 relative tothe collar 46 not being detrimental to the performance of the swivelassembly since the amount of axial play will not exceed one pitch of thethreads 68.

In operation it will be apparent that the flexible sleeve 34 is sodisposed relative to the exhaust port 16, and is curved to suchproportions as to be impinged by and to deflect the exhaust fluid streamsubstantially. This impinging action of the exhaust stream with itsattendant pressure waves caused by incomplete expansion of the workingfluid in the tool proper imparts sufiicient energy to the flexiblesleeve 34 to cause it to flex and vibrate sufliciently that those iceparticles present in the exhaust flow are prevented from accumulating inthe exhaust pipe and thereby preventing unwanted restriction in theexhaust system of the tool. The smooth curved shape of the flexiblesleeve 34 and the absence of any sharp corners or shapes that couldpermit the lodging of solid particles also contribute to the preventionof ice particle accumulation. Although a curved or bent configurationassures impinging flow of the exhaust stream and more eflicientoperation of the exhaust pipe assembly, a straight sleeve would absorbexhaust flow pulsations to an extent that substantial flexing of thesleeve would still occur. In the illustrated embodiment it will be notedthat the curved portion of the pipe assembly is not a circular arc.Experimentation has determined that a basically elliptical shapedcurvature is more effective in preventing ice accumulation and it isbelieved that this curvature allows more direct impingement by a greaterportion of the exhaust flow and thereby transfers more energy of impactto the flexible sleeve. Singularly significant is the use of thechloroprene elastomer material for the flexible sleeve 34 which has suchsmooth surface character that it also aids in the prevention of iceaccumulation.

Of no less importance is the fact that the unsteady and variableamplitude vibration of the flexible sleeve 34 also serves to impart adegree of cancellation of the pressure waves present in the exhaust flowwhich manifest themselves in the form of audible sound. In additionsound attenuation capability of the manifold assembly is enhanced by thelayer of air insulation formed between the major portion 35 of thefiexible sleeve 34 and the relieved portion 30 of the tubular member 25.

As previously mentioned, a section of flexible hose 26 (FIG. 1) may beattached to the downstream end of the tubular member 25 by being snuglypositioned over the raised portions 76 and 78 and held suitably secureby the same in a manner well known. The exhaust flow can then beconducted any desired distance from the operator and given directionalattitude suflicient to obviate any further need for treatment to reducenoise.

Having shown that the invention has particular novelty and utility, itwill be appreciated that application to the tool 10 would not be alimitation in its use but that a number of expansible chamber devicesutilizing compressed air and subject to the problems herein solved couldenjoy the benefits of the invention.

What is claimed is:

1. (a) An expansible chamber tool operable by compressed air and havingan exhaust port for conducting expanded exhaust air from said chamber,said expanded exhaust air containing ice particles formed therein as anincident to expansion;

(b) an exhaust pipe assembly having one end connectable with saidexhaust port for receiving said exhaust air and ice particles therefrom;said exhaust pipe assembly comprising; i

(1) tubular conduit means in communication with said exhaust port;

(2) flexible tubular sleeve means having a major portion disposed withinsaid conduit means for flexing in response to exhaust fluid flowtherethrough whereby such flexing prevents the accumulation of said iceparticles in said exhaust pipe assembly, said flexible sleeve is securedadjacent said end of said exhaust pipe assembly which is connectablewith said exhaust port, and the remainder of said sleeve being generallyof like configuration with respect to said conduit is disposed in spacedrelation therein, and

(3) said exhaust pipe assembly is curved sufficiently for expandedexhaust air flowing therethrough to impinge on said sleeve to flex thesame.

2. The invention set forth in claim 1 wherein: 5 said flexible sleevecomprises a smooth surfaced hollow body molded of a chloropreneelastomer.

References Cited UNITED STATES PATENTS MARTIN P.

FOREIGN PATENTS Great Britain.

SCHWADRON, Primary Examiner.

I. C. COHEN, Assistant Examiner.

U.S. Cl. X.R.

